Innate immunity and regeneration in East African rodents

Although every animal is injured at some point during its lifetime, how an injury heals is variable across species. Some are capable of regenerating damaged tissues while others seal the wound with a scar. Discovering the mechanisms that induce tissue regeneration in wild animals remains one of the great, unanswered questions in biology. Why can salamanders re-grow amputated limbs, but squirrels cannot? A particularly intriguing hypothesis, though poorly investigated, is the apparent loss of regenerative capacity during tetrapod evolution in favor of a strong adaptive immune response to protect against infection, the result of which is excessive fibrosis and a failure to regenerate damaged tissue. For homeotherms, enhanced specificity of the immune response coupled with rapid wound closure and scarring has been viewed as a selectively advantageous solution to injury in the face of persistent microbial threat. Our recent discovery that wild African spiny mice (Acomys) are capable of regenerating skin, hair follicles, and cartilage, represents one of only a handful of documented cases of genuine tissue regeneration in wild, pathogen-exposed, immunocompetent adult mammals. Furthermore it indicates that there is considerable interspecific variation in regenerative ability among some wild mammalian populations. This proposal aims to discover if other rodents occupying the same habitat as Acomys also possess enhanced regenerative ability, and if so whether enhanced regenerative ability is accompanied by changes in immune function.